1. Field of the Invention
The present invention relates to a method and system for fractionating whole blood into its components and to a separation chamber within which blood is fractionated.
2. Description of the Prior Art
Heretofore, various methods and systems have been proposed for fractionating whole blood into the components thereof. Such prior art methods and systems have involved intervivos blood processing in which whole blood is taken from a live donor, separated within a processing system into its constituent components and a desired component (or components) is segregated for collection followed by returning the remaining blood fluid to the donor.
Whenever a live donor is supplying the blood to be fractionated there are always hazards involved and various protective steps have to be taken to insure that no harm comes to the donor. Examples of the various safeguards that need to be taken are explained in greater detail in the related co-pending application Ser. No. 843,222 referred to above. Also, in order to collect large numbers of white blood cells and platelets a healthy donor is usually required. This process for processing whole blood taken from a live donor is referred to as cytopheresis or plasmapheresis.
One previously proposed closed system for fractionating whole blood utilizes four plastic bags interconnected by plastic tubing. All the bags are placed in a centrifuge device and whole blood in a first bag is then centrifuged. Red blood cells collect at the bottom of the bag, white blood cells in the middle, and plasma collects at the top. A "plasma express" tubing which is closed inside is connected to the top of the bag and has an "in-line" cannula therein. After the first centrifuging, the cannula is moved in the tubing to open same and plasma and platelets are expressed from the first bag into a second bag by applying pressure to the first bag. Then the second bag is centrifuged to separate plasma from platelets and followed by expressing the platelets and plasma into respective third and fourth bags. This system requires operator intervention and takes several hours to complete. Also the efficiency of the separation is approximately 50%.
As will be described in greater detail hereinafter, the method and system of the present invention enables one automatically and efficiently to fractionate in a closed, sterile environment, previously collected stored quantities of whole blood or blood collected directly from a donor into the components thereof. It is estimated that by utilizing the blood fractionating method and system of the present invention, three pints of banked whole blood can be processed automatically in a closed sterile environment to produce quantities of the fractionated components thereof equivalent to the quantities of these components that would be obtained by extended cytopheresis or plasmapheresis and with an efficiency of fractionation of 90% or better.
Another advantage of the blood fractionating method and system of the present invention is that a donor can supply quantities or whole blood at different times, i.e., in batches--pints of whole blood stored in blood bags, and then each whole blood bag can be processed by the method and system of the present invention at any desired time without requiring a donor to be connected to the apparatus.
Also, and as will be explained in greater detail hereinafter, a further advantage of the method and system of the present invention is that any given quantity of whole blood can be more completely and better utilized by dividing it into desired components and distributing the components to different recipients. The economy arises because any given transfusion is made for the purpose of replenishing a single component, for example only red blood cells are needed, and the other components such as white blood cells, platelets and plasma will not generally contribute to the treatment and many times are injurious by virtue of their volume, particularly in the case of plasma, or by virtue of their incompatible antigenic nature, particularly in the case of white blood cells. Also, infusion of any blood component not actually required by the recipient is a waste of a vital and hard to obtain resource.
Moreover, as will be explained in greater detail hereinafter, the present system provides for the removal of certain plasma proteins, in particular, Immunoglobulin A, by removing the plasma and washing the red blood cells. In other words, removal of the plasma from the red cells removes Immunoglobulin A which has been shown to sensitize recipients and can be a cause of transfusion reactions. Sensitizing is a biological description of the process whereby an individual recognizes an antigen and gets an immune response, such as with allergies or hay fever.